Power converters that use pulse-width modulation techniques to convert three-phase AC input power to one or more DC power levels are widely known. These converters typically comprise three individual converter stages that may be connected in either a delta or a wye configuration. In a delta configuration, each converter stage is coupled between two of the three phases, .phi.A, .phi.B and .phi.C. In a wye configuration, each single phase stage is coupled between a single phase and neutral. In each stage, a switch is closed to generate an increasing current in an inductor that is coupled to one of the phase inputs. When the switch is opened, the current in the inductor is diverted to a large storage capacitor. The current that is pumped onto the storage capacitor when the switch is open creates a DC voltage on the capacitor.
Since the voltage on the storage capacitor in each single phase stage is not at the same level as the voltages on the storage capacitors in the other stages, the stage outputs cannot be coupled in parallel. Therefore, each large storage capacitor is coupled to a separate DC/DC converter. The outputs of the three isolated DC/DC converters may then be coupled together to form a single DC supply, where each stage provides one third of the total output power.
The above-described power device thus converts a three-phase AC input to a DC level using three single-phase boosts and three DC/DC converters. This architecture contains a considerable number of redundant components. This adds to the cost of the power device, increases the amount of circuit board area required by the power device, and adds additional weight to any system in which the power device is installed.
Accordingly, what is needed in the art is an improved power supply converter that minimizes the number of components needed to convert three phase power to a DC level. In particular, there is a need in the art for an improved power supply converter that utilizes only a single DC/DC converter to convert DC outputs received from three separate converter stages.